The push-pull electrostatic loudspeaker disclosed in Patent Document 1 includes two flat electrodes opposed to each other with a clearance therebetween and a membranous vibrating plate (vibrating member) having conductibility and disposed between the flat electrodes; when a predetermined bias voltage is applied to the vibrating plate and the voltage to be applied across the flat electrodes is changed, the electrostatic force exerted to the vibrating plate is changed, whereby the vibrating plate is displaced. When the applied voltage is changed depending on an acoustic signal to be input, the vibrating plate is displaced repeatedly depending on the change, and an acoustic wave depending on the acoustic signal is generated from both faces of the vibrating plate. The generated acoustic wave passes through through-holes formed in the flat electrodes and is radiated to the outside.
Furthermore, as an electrostatic loudspeaker having flexibility and being foldable or bendable, the electrostatic loudspeaker disclosed in Patent Document 2 is available. In the electrostatic loudspeaker, a polyester film (vibrating member) on which aluminum is evaporated is held between two pieces of cloth (electrodes) woven with conductive threads, and ester wool is disposed between the film and the cloth.